1. Field of the Invention
The present invention relates to a band-applying apparatus for use in a packing system, which comprises a plurality of roller units, each having a driving roller and a driven roller (touch roller), and in which a band is fed, pulled back and tightened, while being clamped between the driving roller of each roller unit and the driven roller pushed onto the driving roller. The invention also relates to a band-applying method for use in a packing apparatus.
2. Description of the Prior Art
Packing systems, so-called xe2x80x9cband-wrapping packing systems,xe2x80x9d are known, each designed to pack an article by wrapping a band around the article and tying the ends of the band together. The band-wrapping packing system has a band-applying apparatus that comprises roller units, each including a driving roller and a driven roller. The driving roller of each roller unit feeds a band, pulls back the band, and tightens the band. The driven roller contacts the driving roller, clamping the band between it and the driving roller. The driving roller is rotated in the forward direction to feed the band reliably, while preventing the band from slipping on the driving roller. The driving roller is rotated in the reverse direction to pull the band back and tighten the same.
Japanese Patent Application KOKAI Publications Nos. 05-170217 and 05-338615, for example, disclose band-applying apparatuses for use in packing systems. Either apparatus has three roller units, each comprising a driving roller and a driven roller. The three roller units are designed to feed a band, pull it back and tighten it, respectively. The driving rollers of the roller units are a feed roller, a reverse roller or a tension roller. The feed roller feeds the band when it is driven in the forward direction. The reverse roller pulls back the band to wrap it around an article to be packed when it is driven in the reverse direction. The tension roller tightens the band when it is driven in the reverse direction.
Japanese Patent Application KOKOKU Publication No. 57-23611 discloses a band-applying apparatus for use in packing systems. This apparatus has two roller units, each comprising a driving roller and a driven roller. The first roller unit feeds a band and pulls it back. The second roller unit tightens the band. The driving roller (i.e., feed roller) of the first roller unit is rotated in the forward direction to feed the band and in the reverse direction to pull back the band. On the other hand, the driving roller (i.e., tension roller) of the second roller unit is rotated in the reverse direction to tighten the band. That is, the feed roller not only feeds the band, but also pulls back the band. In other words, the feed roller functions as a reverse roller, too.
Japanese Patent Application KOKOKU Publication No. 04-36928 discloses a band-applying apparatus for use in packing systems. This apparatus has two roller units, each comprising a driving roller and a driven roller. The driving roller of the first roller unit is a feed roller that rotates in the forward direction to feed the band. The driving roller of the second roller unit is a reverse roller that rotates in the reverse direction to pull back the band and tighten the same. That is, the reverse roller functions as a tension roller, too.
A driven roller (i.e., tough roller) usually comprises a roller body, a bearing such as a ball bearing, and is supported on a support member such as a support arm. A driving member such as a solenoid or a cam rotates the support member.
The band-applying apparatuses disclosed in Japanese Patent Application KOKAI Publications Nos. 05-170217 and 05-338615 have three rollers units, each comprising a driver roller and a driven roller. Having many components, they are complex in structure. Nevertheless, the three driving rollers (i.e. feed roller, reverse roller, and tension roller) need not be rotated in both the forward direction and the reverse direction. They need to rotate in one direction only. More specifically, the driving roller (i.e., feed roller) for feeding the band is driven in the forward direction only, and the roller (i.e., reverse roller) for pulling back the band and the roller (i.e., tension roller) for tightening the band are driven in the reverse direction only. Thus, the motor and the reduction-gear mechanism can be small and simple.
The band-applying apparatus disclosed in Japanese Patent Application KOKOKU Publication No. 57-23611 has two roller units, each comprising a driving roller and a driven roller. The driving roller (i.e., feed roller) of the first roller unit is rotated in the forward direction to feed the band and in the reverse direction to pull back the band. Thus, the feed roller functions as a reverse roller, too. The apparatus is therefore simpler than otherwise. However, the feed roller must be driven in the forward direction to feed the band and in the reverse direction to pull back the band. Inevitably, the motor and the reduction-gear mechanism are large and complex in structure. Japanese Patent Application KOKOKU Publication No. 57-23611 further discloses another band-applying apparatus in which one touch roller is attached to one end of a support arm and is pushed onto the feed roller or the tension roller by rotating the support arm. In this apparatus, the same touch roller can contact the feed roller and the tension roller. This helps to simplify the structure.
The band-applying apparatus disclosed in Japanese Patent Application KOKOKU Publication No. 04-36928 has two roller units, each comprising a driving roller and a driven roller. The reverse driving roller functions not only as a reverse roller, but also as a tension roller. Therefore, the apparatus has a simple structure. The driven roller can be driven. The reverse roller (i.e., driving roller) is driven to pull back the band, and the driven roller (i.e., touch roller) of the reverse roller is driven to tighten the band. That is, the driven roller is pushed onto the driving roller, clamping the band between it and the driving roller, when the band is pulled back and when the band is tightened. To pull back the band, the driven roller of the reverse roller is driven and the driving roller is not driven. To tighten the band, the driven roller of the reverse roller is not driven and the driving roller is driven. The driven roller is pushed to the driving roller with a greater force to tighten the band, than in the process of pulling back the band.
In this apparatus, in which the driven roller of the reverse roller is driven, the driven roller is complicated in structure. Further, one roller (i.e., reverse roller) must be driven to pull back the band, and another roller (i.e., touch roller) must be driven to tighten the band. In view of this, too, the apparatus is complex in structure.
An object of the present invention is to provide a band-applying apparatus for use in a packing system, which comprises a small number of components and has therefore a simple structure and which has a small and simple reduction-gear mechanism. Another object of the invention is to provide a band-applying method for use in a packing system.
To achieve the first-mentioned object, there is provided a band-applying apparatus in which a single touch roller is first pushed onto a forward driving roller and then onto a reverse driving roller with two different forces.
More precisely, the touch roller is pushed onto the reverse driving roller with a small force, with a band clamped between it and the reverse driving roller, thereby to pull back the band and wrap the band around an article to be packed. Then, the touch roller is pushed onto the reverse driving roller with a large force, thereby to tighten the band wrapped around the article. Thus, the reverse driving roller functions not only as a reverse roller, but also as a tension roller.
In a band-applying method according to the present invention, a single touch roller works together with both a forward driving roller and a reverse driving roller. The touch roller is first pushed onto the forward driving roller and then onto the reverse driving roller with a small force or with a large force. Hence, the same touch roller serves to feed a band forward, pull it back and tighten it. In other words, the band can be fed, pulled back and tightened, merely by moving the touch roller between the forward driving roller and the reverse roller and controlling the force with which the touch roller is pushed onto the reverse driving roller.